Telephone call distributing system



May 27, 1952 l H. w. BALZER 2,598,098

A TELEPHONE CALL DISTRIBUTING SYSTEM Filed Aug. 24, 1946 9 Sheets-Sheet l A|2| g77 Am 267 j Al22 Al|2 A2| "AIOI M231 I I I loam Ana 626s F I (L mfgzgss v Y A|03 2 7 l L d" 'MAKING 2 AIO V q; 99959 il I l fA I A25 l. \'u: ,fA|4 n j W lAzs 84,5 I 0 o o o o TI I o g a a o e g5' o o I AOZ C B 0 0 D 0 I o' B5' B4' o l I an O C O D O C O 0 D 0 0 Q C O g I o o o o 0 o o 0 0| o o n o 'o o c A o 1k o Z STORAGE swncH :B52 B42 gf'BANKs O o Q 0 0 D 0 l |22 2| -bo o o o o o o o o I 0 D D O O O O @I g o o o o o oss Z 0 G 0 0 I B33 B43 O 0,| D O 9 6 0 9 0 O Q IN o o| I3@ n o e o o o o o o oI Q 0 0 0 O O C 0 0| 0 0 o O 0 Q 0 D o ko B24 0I o o o o o o n @B34 B44 o L B|4 0 0 0 0 C l O 0 DI 0 a |4 u| I TLQ 0 0 O 0 O O 0 0l x .|I-ol0 e A? I E I g vERTlcAL s: BANK l L l I S y o 9 e 7 6 5 4% zl STORAGE START RESISTORS IN VEN TOR. HARVEY W. BALZER ATTORNEY May 27, 1952 I H. w. BALZER v2,598,098

TELEPHONE CALL DISTRIBUTING SYSTEM Filed Aug. 24, 194e 9 sheets-sheet 2 FIG. 2

TOLVL LINE CIRCUIT 250 GEN.

CENTRAL OFFICE TOLL LINE CIR.

TOLL LINE CIR. 270

INVENTOR. HARVEY W. BALZER ATTCRNEY May 27, 1952 H. w. BALzER TELEPHONE CALL DISTRIBUTING SYSTEM Filed Aug. 24,1946

9 Sheets-Sheet 3 o 5 2 m. C E N l- L o T HARVEY W. BALZER ATTORNEY May 27, 1952 H. w. BALZER 2,598,098

TELEPHONE CALI.. DISTRIBUTING SYSTEM Filed Aug. 24, 1946 9 Sheets-Sheet 4 HARVEY W. BALZER Zzk/ ATTOR NEY May 27, l952 I-I. w. BALzER 2,598,098

TELEPHONE CALL DISTRIBUTING SYSTEM Filed Aug.' 24, 194e 9 sheets-sheet 5 FIG. 5

- IN VEN TOR. HARVEY W. BALZER ATTORNEY 9 Sheets-Sheet 6 RTS ATTO R N EY OSA I sox/.-

INVEN TOR. HARVEY W. BALZER May 27, 1952 Filed Aug. 24, 194e Lsol Leo /FBls FIG. 6 STORAGE CONTROL OIR. 600

May 27, 1952 H. w. BALZER 2,598,098

TELEPHONE CALL DISTRIBUTING SYSTEM Filed Aug. 24, 194e 9 sheets-sheet 7 Fla? Leon 1.6021

I STORAGE ooNTRoL cm. soo HLST' I l l l .IN V EN TOR. HARVEY W. BALZER ATTORNEY May 27, 1952 H. w. BALZER TELEPHONE CALL DISTRIBUTING SYSTEM 9 Sheets-Sheet 8 Filed Aug. 24, 1946 3 H S I n m T 2T. 2222.2; l AZNQNSN .l.. 1|# H2 .MLLLLL S 4 6N T T Lly. u l 4 l M n m 2 2 .2 P i T n m G ,/.u 3 u n R S s (.Nlilll 2 m. w G S L O m 2 N E E QV R E m.. T E6 M U U G M. T P P R R Sm 0 m www 22 no mm To ALL sroRAGE ASB BUSY METER ma n Nz m EL 0 VA Na U IW. A vn E .V R l A H n Y P B E uw ms m.. M u m 2 2 |...W T RM DL FA I2 M m M A M -2 -2 P RT A May 27, 1952 Filed Aug. 24, 1946 COMMON H. W. BALZER TELEPHONE CALL DISTRIBUTING SYSTEM FIG. IO

FIGB

FIG. I

FIG.8

FIG. 7

FIG. 5

9 Sheets-Sheet 9 JNVENTOR. HARVEY W. BALZER BY l ATTORNEY Patented May 27, 1952 TELEPHONE CALL DISTRIBUTING SYSTEM Harvey W. Balzer, Downers `Grove, Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application August 24, 1946, Serial No. 692,884

The present invention relates to telephone systems in general and, more particularly, to improved arrangements for distributing calls to the operator positions of a switchboard in which the calls are routed to individual operator positions by nder switches. f

Specically stated the present embodiment of the invention lies in an improved arrangement for distributing calls to the operator positions of an automatic toll switchboard of the type disclosed in the Imre Molnar Patent No. 2,361,313, issued October 24, 1944. The lines and trunks, over which calls may be directed to the operator positions of a switchboard of the type referred to, have their conductors multipled to terminals in the banks of finder switches which are associated with individual operators positions. When a call is originated by a line or trunk, the test terminals of the calling circuit are marked in the nder banks and a nder switch associated with an idle operator position hunts for the marked test terminals which, when found, cause the nder switch to connect the calling circuit to the idle operator position. The finder banks are so arranged that relatively little movement of the iinder is required to connect to the terminals of some of the lines while a relatively large movement of the nder is required to connect to the terminals of other lines. At times when the traiiic on the switchboard becomes heavy and a number of incoming calls are waiting to be answered, a circuit with terminals in relatively unfavorable positions in the nder banks may wait considerably longer than the average answering time for calls in this period. Numerous methods have been used to improve this condition among them the practice of slipping the multiple so that the terminals of every circ'uit have a relatively favorable position in some of the iinders. Another method makes waiting calls accessible to the operator positions in groups so that calls originating after a group of calls becomes accessible to the operator positions cannot be answered until all of the calls of the group have been answered. Both of the above methods tend to prevent the maximum answering time from becoming excessive in comparison to the average answering time.

It is the aim of the present invention to distribute calls to the operator positions of a switchboard in relatively the same order that the calls are received at the switchboard so that the maximum answering time will be the shortest possible and willbe governed mainly by the availability of an operator to answer the call. The arrange- 31 Claims. (Cl. 179-27) ment is effective so long asthe number of calls waiting to be answered-does not exceed the number of storage switches.

To accomplish this purpose there is provided a marking control circuit for each circuit on which incoming calls may be received, a group of storage switches, a storage control circuit common to the group of storage switches, and a storage distributor having relays individual to each of the storage switches. It may be noted that thecall storage feature is effective only for incoming calls and that when the marking control circuit is associated with a two Way line or trunk it has no function to perform on outgoing calls.

The start leadtof each circuit, normally connected tothe common start circuit of the finder switches associated with the operator positions of the switchboard; is connected individually to a relay in the associated marking control circuit. The'test leadv of each circuit is connected to the associated marking control circuit and extended by the marking control-circuit to test terminals which appear in the'banks of the finder switches. A start lead from each marking control circuit is connected to the common start lead of the finder switches.

The marking control circuit is connected in multiple to terminals in the banksl of the group of storage switches and Ais also connected to the common storage control circuit thru which the operation ofthe storageswitches is started. When a call is received on one of the circuits, a relay in the associated marking control circuit is operated over the start lead. This relay connects markings to the test terminals multipled thru the banks of the storage switch group and causes a relay in the storage control'circuit to operate. The storage control circuit thru the storage distributor closes a start circuit to an individual one of the storage switches andk causes this switch to hunt for the markings set' up in its banks by the marking control circuit.

The storage switch finds the marked bank terminals and thru some of them connects itself to the marking control circuit causing this circuit to disconnect its markings from the banks of the storage switches.j The storage distributor then connects another one of the storage switches to the storage control circuit so thatthis other storage switch may hunt for and connect to a marking control circuit operated by a subsequent incoming call and the storage distributor also operates to insure thatthe call connected to by the first storage switch will be accepted by an 3 operator position before any subsequent call is accepted.

At the time that an operator position accepts an incoming call, the storage control circuit, the storage distributor and the storage switch connected to the first waiting call are controlled from the operator position to operate the marking control circuit to extend the test lead of the incoming circuit to the test terminals of the finder switches associated with the operator positions and to close a circuit to the common start for the iinder switches. One of the finders, associated with the answering operator position will hunt for the marked test terminal and connect the operator position thru to the incoming circuit. The connection of the finder switch to the incoming circuit further operatesV the marking control circuit to place it under control of the calling circuit and the operator position and to release the connected storage switch. The storage switch on releasing is returned to control ofV the storage distributor and becomes available for other connections. TheV storage ldistributor jat this time also makes available to operator positions the incoming circuit associated with-i thednextstorage switch.

` A; control key. is provided which, whenV operatled,`rmakes thestorage feature inoperative and placesthe marking control circuit directly under control of its associated circuit. Another con-` trollkey is provided which, when operated, makes thestorage feature ineffective until all available operator` positionsarebusy. When one or more incoming callsare Waiting to beanswered and all operator positions are busy, the storage feature becomes eiective and will remain sountil all stored calls are answered and an .operator positionis available to accept an incoming call.

While only one group of storage switches, one

storage control circuit and one storage distributor ..1

are "shown, it may be noted that similar-apparatus can be arranged so that different groups of cirouitscan `be accepted thruv different groups of storages switches byother operator positions.

It is an` object of the present inventionto provide for distributing calls to theoperator positions of a switchboard in the sameorder that the calls are received at the switchboard.

It is l another object of the invention to .provide for storing `calls in thesequence in which they arereceivedat the switchboard and subsequently distributing the calls to theoperator positions of theswitchboard in the same sequence.

@ne feature'of the invention is to provide, for each circuit on which incoming callsmaY be received, a marking control circuit which makes `ther'narking for vthe incoming call effective in thender banks after the marking control circuit has .been operated under ther joint control of its Vassociated circuit, one of the storage switches, andan operator position.

Another feature of the invention provides for operating the marking control circuit from its associated line independent of the storage switches.

Another feature of the invention provides storage vswitches that accept calls, under .control of a storage distributor, in theorder that the calls are'received at the switchboard, store the calls,

and release the calls vto operator positions, under` a control key for making the storage switchesand- 4 storage distributor effective only in case all opil`` ator positions are busy, after which the storage switches continue to function until all stored calls have been accepted by operator positions and idle operator positions are available to accept calls as they are received at the switchboard.

A further feature of the invention provides for releasing a storage switch as soon as the call storedtherein has been accepted by 1an` operator position, the storage switch immediately returning to its proper position, under control of the storage distributor, for accepting and storing a subsequent call.

A still further feature of the invention provides a` timing device for automatically operating the kstorage control circuit and the storage distributor in case the storage switch that is conditioned to accept a call does not start or if a call is released ,from storage and is not accepted by an operator position.

Another feature of the invention provides a control device for releasing all calls from storage.

Another feature of the invention provides for testing the storage switches, the storage control circuit and the storage distributor.

The above features and others not particularly mentioned at this time will be described.A in detail in thefollowing specifications with the aid of the accompanying drawings comprising Figs. 1 to -10 inclusive, Fig. 10 illustrating the manner in which Figs. 1 9 shall be assembled.

Fig. l1 shows one marking control circuit in detailconnected to the banks of a storage switch, and by block diagrams two similar marking control` circuits with connections to thebanks of the storage switch;

Figs. 2 and 3 show one tollline circuitin detail with connections to the marking control circuit Ain Fig. 1 and to a switchboard in a distant exchange and two similar circuits are shown by block diagram with connections to marking control circuits in Fig. 1;

Fig. 4 shows the storage switch associated with the banks in Fig. 1;

Fig. 5 shows the storage distributor circuit with storage distributor relays for the storage switch n.Fig. `4 and similar relays for connection to two similar switches;

Figs. 6-8 showi the storage controlcircuit with connections to Figs. 1, 4 and 5 andalso to aposltion distributorcircuit such as shown in Fig. 9; andk Fig. 9 shows anoperator position withan associated finder switch, a call switch, a postiondistributar and a common start circuit. I

There is a large number of line circuits, such as ringdown Vtoll lline circuit 250 shownin Figs. 2 and3, each connected to a distant toll switchboard such as toll switchboard 20|. 'Ihe leads of .these lines terminate in the -banks of finder switches suchas finder switch 980 and are mult-iplied to the banks of other similar finder switches. Eachtoll line` oircuitis connected to a marking control circuit such vas circuit A, Fig. 1. It may be noted that Figs. 2 and 3 ofthis drawing are similar to Figs. 2 and 3 of the drawing forthe Imre` Molnar Patent No. 2,361,313, and can be substituted for the corresponding figures vin the above ,mentioned patent. and that thereafter Figs. 1 and 4 `tort-inclusive may beappliedto Patent No. 2,361,313.

The marking control circuit A, in Fig. 1 is individualto thetoll line circuit 250, and wis one .of a numberof such circuits, two of which ,are indicated atA1 and A2 associated with toll line-circuits 260 and 270 respectively. The marking control circuits, such as A, are connected to the banks of storage switches, such as the storage switch banks in Fig. l, which are individual to storage switch 400, Fig. 4. There are a number of storage switches, such as 400, each having similar banks and having wipers such as wipers WI I to WI5 inclusive.\ The marking control circuits, such as A, are connected to each of the storage switch banks so that each of the storage switches has access to any one of the marking control circuits by means of its associated banks and wipers.

The marking control circuits, such as A, are also connected to storage control circuit 600, which is shown in Figs. 6, 7 and I8. When a marking control circuit is operated by its associated line circuit, in response to an incoming call on the line, the marking control circuit causes the storage control circuit to operate and extend a starting circuit thru the storage distributor 500, shown in Fig. 5, to one of the storage switches, such as storage switch 400. The storage switch is a finder switch of the well known vertical and rotary type which iirst hunts for a marked level and then hunts for a marked terminal in the marked level. When its wipers are moved to the terminals of an operated marking control circuit, the storage switch stops and, thru its wipers, re- `mains connected to the marking control circuit. The connection of the storage switch to the marking control circuit further operates the marking control circuit to remove its markings from the storage switch banks thus preventing another storage switch from connecting to the found marking control circuit.

The storage distributor 500 operates under control of the storage control circuit 600, selecting individual storage switches to hunt for operated marking control circuits, and marking the storage switches in the order of their selection, for release under control of operator positions, such as operator position 9i0. As each storage switch connects to a marking control circuit, the storage distributor operates and selects another storage switch to hunt for operatedmarking control circuits and as each storage switch releases, the storage distributor operates to make another storage switch accessible to the operator positions. Operator positions such as operator position 9| 0 have access to the storage distributor thru the position distributor circuit 920 and the storage control circuit 600.

A timer, connected to the storage control circuit 600, is started each time the storage control circuit is conditioned to start a selected storage switch. In case the storage switch does not function, 'and the storage control circuit cannot advance the storage distributor within a pre-determined time, the timer will cause the storage distributor to be advanced, and another storage switch will be selected to connect to the marked terminals.

The iinder switches, such as iinder switch 900, the operator positions, such as operator position 910, the position distributor circuit 920, the common start circuit 930, and the call switches such as call switch 940 are of the type shown in the Imre Molnar Patent No. 2,361,313, which may be referred to for a detailed description of these circuits.

The nder switches, such as 900, are of the well known vertical and rotary type having banks and wipers suitable for engaging the bank contacts. Circuits suitable for receiving incoming 6 calls terminate in the bank contacts of the `finder switches. Control leads for these circuits maybe taken thru marking control circuit A. The nder switches are connected to operator positions, such as operator position 9I0, and constitute one end of the connecting links in the operator positions.

The operator positions such as 9|0'each have a number of connecting links which terminate on one end in nder switches, such as nder switch 900, and on the other end terminate in call switches, such as the call switch 940. Each operator position includes a telephone circuit and common equipment for performing the services of a toll operator. The operators telephone circuit and common equipment are connected to the links by control keys and relays individual to the links. Each operator position is connected to the position distributor circuit 920 and to the common start circuit 930. 'I'he position distributor circuit 920 is connected over the lead DST to the storage control circuit, Fig. 8. The common start circuit 030 is connected to marking control circuits such as marking control circuit A.

The call switches, such as call switch 940. are of the well known vertical and rotary type having access thru banks and wipers to toll line circuits, such as toll line circuit 250, and to other lines and trunks by means of which the operators can establish connections to other ofces or to'local subscriber lines in the central olilce |00.

The storage release key, SRK, when operated, releases all operated storage switches. With the key SRK operated, the marking control circuits operate under control of their associated lines and nder switches -such as the nder switch 900.

The no storage key, NSK, when operated, allows all stored calls to be answered in sequence but prevents the storage of additional calls. After all stored calls have been answered and with the key NSK operated, the marking control circuits operate under control of their associated lines and finder switches such as the nder switch 900. Y

The storage control key, SCK, when operated, permits the marking control circuits to operate under control of their associated lines and finder switches, such as finder switch 900, as long as an idle operator position, such as operator position 9I0, is available to answer calls. With the key SCK operated and with all operator positions busy, the marking control circuits will operate under control of their associated lines, and'v storage switches, such as storage switch 400, which will store incoming calls received under this condition and later release these calls to operator positions in the same order that they were received. Should the key SCK remain operated after all stored calls have been acceptedby operator positions and an operator position has become available to accept calls, the marking control circuits may again be operated under control of their associated lines and Aiinder switches such as nder switch 900. A

The routine test key, RTK, is provided for testing the performance of the storage. control circuit 600, the storage distributor 500, and, in sequence, each of the storage switches, such as storage switch 400. Terminals in the banks of each of the storage switches are connected to the storage control circuit and are markedby the operation of a relay controlled by the operation of the key RTK. This key also causes the storage control circuit and the storage' dis- V.tuxrlature 36 I.

tributor; to operate vone of -the storage switches .which in turn connects itself tothe marked terminals. 'Iheconnection ofa'storage switch to themarkedterminals operates another relay in the storage control circuit which causes the storage; switch to release and the storage 'distributor torselect another storage switch. This storage switch `in turn connects to the marked terminals, releases and Apermits the operation of manother `storage lswitch under control of the storage control circuit and the storage distributer. The operation and release ofthe storage switches one at a time continues until the key RTK is restored. To make certain thatV the routine test of this equipment does not interfere with regular calls, therkey SRK -should be operated, to release all stored calls, before the -keyuRTK is operated, and the key SRK should remain `operated until after the key RTK is restored. The `timer connected to the storage control: circuit functions when the routine test is performed to advance the storage distributor in case one of the storage switches fails tostart yor togrelease. The difference in time required for ktheadvancement of the storage distributor by the operation. and release of a storage switch and that required by the timer is great enough to` permit the tester to determine that faulty operation has occurred and by observing the opr,eration of the individual storage switches the faulty switch can be detected.

Under normalv conditions, immediately after battery has been connected to the storage control circuit 600 and before any incoming calls have been received, the relay SR2 is operated from ground at armature SR|I and closes a circuit to the relay NS thru armature SR22 and `contacts NSKI to ground. The relay NS operates and at armature NSI vcloses a circuit to the -relay PAZ from ground at key SCK. The relay PAZ operates and connects the relay CIS .thru armatures PA22 and SR23 to the storage switch 400 over lead L602 which is multipled to all storage switches controlled by the storage control circuit 500. The relay FBI is energized from. ground over leadLG'l and at armature AFBII closes ra circuit to the relay FB2 which operates and connects the relay STI thru arma,-

,tures -FB2|, PA23, and NS2 over lead L6I8 to Lthe storage start resistors in Fig. 1. thru armatures PA2| and NSS is connected over ,lead L6|2 to the make contact associated with armature AI 5 and to similar contacts in all mark- Ground ing control circuits, such as A| and A2 associated Awith storage control circuit 600.

Assume now that a call is initiated at the toll switchboard 20| over line 25| which terminates in the'toll line circuit 250 shown in Figs. 2 and '3; When the toll line is seized at the toll switchboard and ringing current is projected thereover, the shaded pole, alternating current, ring-down relay R245 is actuated and thereby opens the energizing circuit. for the slow-torelease signal relay R240. lThe relay R240 restores and closes an energizing circuit from :ground thru armatures 24|, 30| and 32|, recti- .er 33|l lower winding of start. relay R350, to

battery. Start relay R350 completes a locking circuit for its lower winding from.k ground at This locking circuit for the start relay R350 .is provided so that the relay will remain operated after the ringing has ceased andthe normally operated signal relay has been permitted to operate again. The, start. relay R350 at armature 353 disconnects idle indicat- ,thru armature FI I .8 img batterypotential from conductor C3'I3and connects conductor C313 to ground `toprevent the seizure o toll line circuit 250 for-outgoing use at central office |00. At armature 355, start relay R350 connects battery potential .by way of the winding of the seizure relay R360 and' lead A IIJI Lto armature A2| in Fig. 1, and

atarmature 356 closesa circuit thru armature 365lead A|02 and the upper winding of the relay AIIVJ, 1, to battery. y vThe relay AIO operates and thru armatures A|4 and A25 connects battery potential toterminals in the storage switch banks. At armatureAIS, relay A|0 connects ground to vertical bank contact 4 and to storage start Aresistor 4 over acircuit which may be traced. from armatures `PA2| and NSS in Fig. f3, lead L6 I2, and armature A26. The ground on vertical bank contact 4 marks this level to the storage switches, suchnras vthe storage switch 400, so that when a switch is hunting it will stop its verticalrlno-V- tion at level vand hunt over the level 4Y for a Waiting call. The ground on the storage start resistor.` is extended thru'rthe lresistor 4, armaf tures NS2, -PA23-and FBZI, andthe windingfof the `relay STI in Fig. "i, to battery, to `thereby operatethe-relay STI. u I Assume ynow that the vstorage control circuit 500 is normal, that the relays FDI1 FD2-FD3 and all similar relays in the storage distributor 500 are not operated, and that all of the relays such as the relay OSI are normal. The relay STI, energizes the relay ST2, Fig. 6, from ground thru armatures KO| and FDAI, contacts ST3I, armatures STIS and VTSI, and theV coilofpthe relay ST2, to battery anduenergizes the relay FDI, Fig. 5, from ground thru armatures FDA2, FD3I, lFDH, FDII, FBIZ, FDAS, STIZ, FII, and the winding of the relay FDI, to battery. -rlfhe relay ST2 operates, connects its winding thru armature STZZ to armature ST32, energizes the lower winding of ST3 from vgrounduat armature STZI, and connects ground thru armatures ST2-3 and'FDA4 to a make contact of the-relay FDI. The FDI relay operates armature FDI 2 first, connecting its winding thru armatures FDI2, FD23 and FD33v to the winding `of the relay FI, which is short circuited by direct ground connected to the winding of relay FDi over a circuit previously traced. 'The relay AFDI operates in full, armature FDII opening the start-ing circuit ,toFDI and opening the short circuit around the winding vof relay FI, armature FD|3 connecting ground over the lead LEII to energize the relay FT in storage switch 400, Fig. 4, and armature FDI4 connecting the lead L5|2 to the winding of the relay FDA. Relay FI operatesfor a The relay ST3. energized as previously vdescribed but Aslightly slow tooperate because its upper winding is short circuited at armature STBl, now operates its armatures, armature ST33 energizing the upper winding of the relay RTS from ground at' armature STZI, armature ST32 closing a holding circuit to the relay ST2 j fromk ground thru armatures KOI, FDM, ST32 and lST22, and armature ST34 closing a circuit'to the relay OSI"v from ground thru armatures YOSAZ. 0,533,y OS-23, OSI3, OSA3, ST34, and SII., and the winding of relay OSI to battery. The relay OSI operates itsV armature OSII rst, connecting'` ground thru'the winding of the relay Sland armatures OS32, @S22 and OSI-i toits winding. As the OSI'relay continues its operation, it opens its starting circuit at armature OSI3 and thus completes its operation in series with the relay SI which also operates and further opens the starting circuit to the OSI relay at armature SII. The relay OSI at armature OSI3 prepares a circuit to the relay OS2, at armature OSIZ prepares a circuit to the relay OSA over the lead L5I3, and at armature OSI4 prepares a circuit to the OA2 relay over the lead L5I4. The function of the OSI relay will be explained later. The relay FI', Fig. 4, energized over the lead L5I I, operates its armatures, energizing the magnet VERT thru armature FTS over a circuit which may be traced vfrom ground thru armature ST24, contactsv INTI, armatures VTS2, FIG, and SWI, thru the windings of magnet VERT, to battery. The vertical wiper WIS is connected thru armatures FTI and VTS3, the upper winding of the relay VTS and the armature ST25 to the winding of the relay INT. The magnet VERT operates, stepping the wipers WII, WI2, WI3, WI4 and WI5 to the rst level, the wiper WI5 contacting the vertical bank contact I, and at armature VERTI energizing the relay INT. The relay INT operates and at contact INTI opens the circuit to magnet VERT. The magnet VERT restores and at armature VERTI opens the circuit to the relay INT. Assuming that the vertical bank contact I is not marked with direct ground, the relay INT restores and at contact INTI energizes the magnet VERT which operates, moves the wipers to the second level, and energizes the relay INT thru armature VERTI. the circuit to the magnet VERT, which in turn restores and opens the circuit to the relay INT. This action continues until the vertical wiper, WIS, is stepped to a vertical bank contact having direct ground connected thereto, the Wipers being moved one level each time the magnet VERT operates. In this case, the vertical bank contact 4 is connected to ground, as previously described. When the magnet VERT restores and the vertical wiper, WI5, is in contact with thevertical bank contact 4, a circut to the upper Winding of the relay VTS in series with the relay INT may be traced from ground on vertical bank contact 4, wiper WIB, armatures FI'T and VTS3, upper winding of relay VTS, 'L' .armature ST25, winding of relay INT, to battery. The relay INT remains operated thus preventing further operation ofthe magnet `VERT and the relay VTS operates its armature VTS4, energizing its lower winding from ground G thru armatures ST33 and STZI. The relay VTS operates in full, opening the circuit to: its upper winding and the relay INT and connecting the wiper WI4 to the lower winding of the relay RTS at armature VTS3, and at armature VTS2 opening the incomplete circuit to the magnet VERT and preparing a circuit to the magnet ROT. The relay INT now restores and a circuit may be traced from ground thru armature ST24, contact INT, armatures VTSZ, RTSI, FTS, SW2 and the windings of the magnet ROT, to battery. The magnet ROT operates, steps the wipers WII, WI2, WIB and W14 onto the rst bank contacts of level 4 and energizes the relay INT from ground at armature ROTI. The relay INT operates and opens the circuit to the magnet ROT at contact INTI, causing the magnet ROT to restore and open the circuit to the relay INT at armature RO-T'I. If

the Wiper WI4 does not encounter battery po-l,

The relay INT operates and opens.'

n explained later.

10 tential on the bank contact to which it has been connected, the relay INT restores and reoperates the magnet ROT which in turn steps the wipers to the next set of bank contacts and reoperates the -relay INT from ground at armature ROTI. the wiper WI4 encounters battery` potential on the bank contact to which it is stepped. Assuming that none of the other contacts over which the wiper WI4 passes have battery potential connected to them, then when the Wiper WI 4 is stepped onto the seventh contact, a circuit is completed from battery thru armatures AI4 and A25, wiper WI4, armatures FTI and VTS3. lower Winding of relay RTS, and armature ST26, to ground. The upper winding of the relay RTS is energized from ground at armature ST33 as previously described but is not strong enough to operate the armature RTSI. However, the lower winding of the relay RTS co-operating with its upper winding operates armature RTSI opening the circuit to the magnet ROT and preparing a circuit to the relay SW.- The magnet ROT restores and opens the relay INT which restores and energizes the relay SW from ground thru armature ST24, contact INTI, armatures VTS2, RTSI and FI4, and the winding of relay SW, to battery. The relay SW operates, opens the incomplete circuits to the magnets VERT and ROT at armatures SWI and SW2, prepares a circuit to the lower winding of the relay SR4 at armature SW3, energizes the relay CIS, Fig. 8, from ground thru armatures SWS,l SRM, 8R23 and PA22, and the winding of relay CIS to battery, closes its own locking circuit from ground thru armatures SWII, VASI and SR42, and energizes the relay FDA, from ground thru contacts BSYI I, armature SWS, the lead L5I2, armature FDI4 and the winding of relay FDA, to battery. The wiper WI 2 when stepped to the seventh set of bank contacts is connected to the grounded terminal of the relay AIU. This ground is extended over wiper WI2, armatures SW6 and FT3 thru the upper winding of the relay SX to battery. The

relay SX operates and a circuit may now be traced from ground at wiper WI2, armatures SW6, SXZ and SW'I, wiper WII, BII, armature A23, and the lower winding of relay AIU to battery. The windings of the relay AIU are connected differentially, and as both windings are now energized in opposite directions the relay AII! releases, disconnecting battery at armature AI4 from the bank contact BI4 so that other storage switches will not connect to the marking control circuit A, and disconnecting ground at armature AI5 vfrom vertical bank contact 4 and from storage start resistor 4 so that other storage switches will not hunt over level 4 unless another marking control circuit associated with level 4 is operated. The relay CIS, which was energized when the relay SW operated, operates and connects the DST lead to the relay OAI, the purpose of which will be The relay FDA, energized by the operation of the relay SW, operates and at armature FDA4 opens the circuit to the re.- lay F'I, at armature FDA3 closes a circuit to the relay FB2, and at armature FDAI opens the circuit to the relay ST2. The relay FD2 operates its armature FD22 iirst, connecting its winding thru armature FD33 and the winding of relay Fl. The relay FB2 then operates in full, opening the circuit to the relay FDI at `armature F1323. 'The relay'uSTZ, opened when This operation continues until ases-,098

the relay FDAl operatedQ restores its armatures.

opening its holding circuit at varmature ST22,

@23mg a part Of'hthe incomplete' gfQuFd Chf' cuit to the leadLrEl I atj armature ST23,' and atv armature ST2I` opening circuits to the relays ST3, VTS and RTS allowing them to restore. Whenthe relay-AIO restores, after thefoperation of the relay SX, ground is disconnected from storage start resistor!! thus opening the circuit to the relay STI which' thereafter' restores its armatures. The relay FT, opened by the operation-ofthe relay FDA, restores its armatures, The relay FDI, opened by the operation of therelay restores its armatures, further opening the-circuit to the relay F'I at armature FDI'S, Yand opening the relay-H3A at armature FDM. The relay FDAr restores, at armature FDAI prepares la lcircuit to the relay ST2, and at armature'FDAlt prepares a circuit to theV lead L52-I. The relaysfD2 and Flfremain operated sothat operation of the storage control circuit in response to other incoming calls willcause the storageswitch lIIIj to connect itselfjto the marking control' circuit associated with the calling line;

It may be noted that-the vertical oir normal springsVONII andVONI`2 are operated at the timethemagnet VERT moyes the wipers thru their first" vertical step; The VON spring 'II prepares a circuitto the release-magnet RLS which is prevented from operating as its circuit is'opened,iirst at armature FII by theY operation of the-"relay lI and later, at armature' SXB, by the operation of the relay SX. A holding circuitto therelay SW may now'betracedwfrom ground thru spring VONI I armatures X6, and 5R02 Vthru;thewindingof-relay SWfto battery. The 'verticalvof normal springA VON I 2 "prepares a Yground circuitto'the leadLI 2 to control "the operation of storage vdistribut'or'iilliiTin'case the FTrelay releasesbefore the SW'relayoperates.

The storage switch- 400v is -nowconnected 'to the marking control circuit A thru" wipers WI I-WI4 inclusive, the relay' SW beingfope'rated from ground at spring'V'ONII andfrom' ground at armature SWI I, and! the relay 'SX being-v operated from ground on wiper -WI 2." Battery thru the-lower winding of therelay AS, thru armatures SWS andYFIB' is connected to the 'lead L5M and'thru armatures OSI4 and OSAI to the winding Yof the vrelay OA2 in`Fig. 7." In marking control circuit A, the relay-AIG is at normal as its two winding-s are energized differentially andthe upperf'windingV of 'the -relay A20 is connected'thruwiperWlS to the storage switchdflli; In the storagev control circuit-600, the',V relay CIS, inadditionf to other' normally operated relays, isoperated overacircuit previously traced, and the DST lead is connected thru armatures`SR2I andCISI "to the winding of* the `relay OAI. In the storage distributor circuit 500; the relays FD2 and'IF'I are operated inv-series and the relays OSI and'SI are operated in series;

Assuming-now that the operator at operator `f position-M0 is ready to receive aV vcallV on the connecting'link'including the finder switch 90,0, the,l operator 'throws' acontrolV key associated with Vthe link causing the` positionA distributor circuit 920itoconnect groundtothe DSTlead The relay AS operates. at varmature ASS energiaes thel relay A20 from'ground thru armatures'2l53, SXI, SWII, wiperWlS, contact B13,l armature AI2 and the upper winding ofthe relay A20, to battery, and 'at armature ASI opens a lhold;- ing circuit to the relay SW and energizes'its own upper winding from ground at armature SWI I. The relay A20 operates, closing a holding circuit'to itself at armature A24 froniground at armature 353, Fig.' 3, connects battery' thru the winding ofthe relay'RSSG, Fig. 3, thru yanna;- tures 355i`Y and A2I over lead 25'I"to-the=tes"t terminals of Ander switches such 'as in'der switch 900, prepares a circuit 'to the commonstart circuit 930 at armature A22, and openstheci-rcuit to the lower winding of therelayiAI-U. The relay AII) is operated by its upper winding' dis"- connectingl the upper winding ofrelayAZ from contact BI3`at armature' AI2, andA connecting ground thruV armatures AII and' A22 overlead C2536" to the common start circuit 930'Which operates and causes the finder`900 to starthunt'- ing over its associated bank contacts:l

Whenthe wipers'ofthe finder 900 'reach the terminals associated withY toll line'circuit 250,

battery potential thru .the windingofthdrelay R360 connected to the nder 900 Vover lead 'C257 stops the hunting action of` thender. Ground, connected at the finder '900 to the lead'CkI, operates the relay R360 which connects a holding circuit toitself at armature 364, opens the-circuit to the upperV winding of therelayAI 0 at armature 365, and opens the circuit to the lower winding or the cutting tool 'I5 from the'rivet hole formed ESSE] restores and at armature-353 transfersv the holding circuit to the relay A20 thruy armatures 36d and A2I to ground 'on lead C251.

The relay. AID'` restores when; its circuit is opened at armature 365 and disconnectsfgrund froin'the leadv'C2530 andthe common. start cir'- cuit'at armature AII; The armature 365 also disconnects ground from" the contact BI2' thus opening'the circuit to relay SX" which restores and at' armature SXS opens the' holdingfcicuit to'relay SW and closes a circuit to the Vrelease magnet RLS from g'roundthru spring VONI'I, armatures SXG and FTI, and the winding of RLS, to battery. The relay SW Vrestoresfat armature SWII opens the circuit' to thefrelay AS which also restores, and at armatureiSWI prepares a circuit to the lead L5I3.` The'release magnet RLS operates and causes the storage switch 40E! to restore its wipers to normal.' The vertical oi normal springs 'are returned to-Ino'rmal when the wipers restore to normal, spring VONII connecting ground thru armature SWII] over the lead L5I3 thru armatures FFDIt'i and OSI2 and the winding of the relay"OSA,' "to battery. The relay OSA operatesand atfarmature OSA?, closes a circuit to the relay OS2-thru armature OSI3. The relay OS2 operatesit's armature O-SZI first, closing a holding circuit to itself thru armature OS32 and the'relay. SI. The relay OS2 completes its operation," opening the circuit to the relay OSI at armatureOS22. The relay OSI restores, at armature OSI2'open'- ing the circuit to the relay OSA, and disconnecting the lead L5M from the storage control circuit at armature OSM. The relay OSA-'re'- stores its armature, opening the starting circuit to the relay O52- at armature OSAS; It"v may?v be noted that the relay SW in restoring opensv the circuitrto the relay CISat armature -SVV-alrlowing relay CIS to restore andfdist :onnectfl the relay 4OAI iiointhelead' DST. The 'relay O-yl 13 restores and disconnects ground from the winding of the relay OA2 which also restores.

'Ihe relay R360 and the relay A20 are held by ground over the lead C251 under control of the nder 900 and operator position 9I0.` When the call is terminated, the operator at operator position 9I0 releases the nder 900 thereby disconnecting ground from the lead C251 to allow relay R360 and relay A20 to release.

Should another incoming call be received on one of the toll line circuits such as toll line circuit 260 either before or after the call on toll line circuit 250 has been answered, the associated marking controlcircuit AI, the storage control circuit 600 and the storage distributor 500 will cause the storage switch 40| to connect itself to the marking control circuit AI in the same manner as explained in the foregoing for the connection of storage switch 400 to marke ing control circuit A. Other relays similar to FEDZ may be interposed between the relay FD2 and the relay FD3 for corresponding storage switches. When the storage switch 40| connects to the marking control circuit AI, the next FD relay will be operated, releasing vthe relay FD2 and preparing the next storage switch to connect itself to a waiting incoming call. In case an incoming call is received before the call stored in storage switch 400 is answered by one of the 4operator positions, the OS relays are not affected by the operation of the FD relays. The relay OSI remains operated until ground is connected to the DST lead by one of the operator positions. The relay OS2 will then operate and the relay OSI release as previously described. The answering of the second call by an operator position will operate a similar OS relay which may be interposed between the relay OS2 and the relay OS3 and release the relay OS2.

The FD3 relay is associated with the last storage switch in the group and is operated when the preceding FD relay is released consequent to the associated storage switch connecting to a marking control circuit. The relay FD3 in operating connects a holding circuit" to itself thru armature FD32, the winding of the relay F2, armature FDI 6, and the winding of the relay FI to ground. The relays FI and F2 operate and a circuit is prepared to the relay FDI thru armatures FII, F2I, FD3I, similar unoperated armatures are other FD relays such as armatures FD2I and FDI I, and armature FBI2 to the armature FDA3. When the storage switch associated with the relay FD3 connects to a marking control circuit, ground over the lead L532 thru armature FDI'I and FD34 operates relay FDA which extends ground thru armature FDA3 over the circuit previously traced to operate the relay FDI. The relay FDI opens the holding circuit to the relay FD3 at armature FDIS and closes a holding circuit to itselffthru armature FDI2, FD23 and F22 to ground thru the winding of the relay FI. The relay FD3 restores and transfers the holding circuit for the relay FDI from armature F22 to armature FD33.

ciated with the relay FDI will connect itself to the marking control circuit of the calling line and the relay FD2 will operate and the relay FDI release as previously described.

The OS relays are operated, in a like manner, in response to the connection of ground to the DST lead which occurs each time a link-in an operator position is conditioned to answer a call. The relay OS3 is associated with the last storage switch in the group Aand is operated when the call in the preceding storage switch is answered by an operator position. The relay OS3 holds in series with the relay SI and the relay s2 which also operate and prepare a circuit to the relay OSI thru armatures SI I, S2I, OS33, similar unoperated armatures on other OS relays such as armatures OS23 and OSI3, to-armature OSAS. When the storage switch associated with the relay OS3 is released by anoperator answering the call stored therein, ground o ver the lead L533 thru armature OSI5, FD35, and OS34 operates the relay OSA which, at armature OSA3, extends ground over the circuit previously traced to operate the relay OSI. The relay OSI operates and opens the holding circuit to the relays OS3, SI and S2 at armatureOSIB, and closes a holding circuit to itself thru `armatures OSII, OS22 and S22 and the winding of the relay SI to ground. The OS3 relay Arestores and transfers the holding circuit vfrom armature S22 to armature OS32. The relay S2, which is slow to release, restores and remains at normal until the relay OS3 is again operated.

The relay FBI is normally energized overthe lead L? thru armature FSI, contacts VONI2, armature SW8,.and lcontacts BSYII, to ground. The lead L60'I is multipled to each of the storage switches in the group. Ground is removed from the lead L60'I by the contacts VONI2 of a storage switch that is oi normal. When allfof the storage switches are 01T normal, the circuit to the relay FBI is opened. The relay FBI restores. aty armature FBI2 disconnecting the armature FDII from the armature FDA3 to prevent operation of the FD relays while all storage switches are oi normal, and at armature FBII opening the circuit to the relay FB2. The FB2v relay restores and at armature FBZI disconnects the STI relay from the storage start resistors to prevent further operation of the STI relay Yifv other marking control circuits are operated while all storage switches are oif normal, and at armature FB22 e connects ground to the ASB leads which may be connected to a meter suitable for registering the all switch busy condition.V

In case the storage switch 400 fails to nd a call waiting on a level over which it is search- 1 ing, or if it fails to switch thru to a waiting call, its wipers are moved to a position beyond the tenth set of bank contacts of the level-and the springs CAMII and CAMI2 are operated. The lower winding of the relay SR4 is energized from' battery thru its lower winding,VV spring CAMI I, armatures FIT and VTS3, lower winding of the relay RTS, and armature ST2 6, to ground. The relay SRA. at armature 8R43, closes a holding circuit to its upper winding from ground at contact VONI I which is operated since storage switch 400 is ofl normal, at armature SR42 opens the incomplete holding circuit tothe relay SW. and at armature SRM opens an incomplete circuit to the relay CIS. GroundI from spring CAMI2 is connected to the lead L5I2 and extended thru armature FDI 4 to the relay FDA which operates, and at armature FDAII opens the circuit to the relay FT. The relay FDA extends ground thru armatures FDA3, FBI2-and FDII to the relay FD2, which operates and releases the relay FDI. The relay FT releases and closes a circuit from battery thru the winding of the release magnet RLS thru armatures FTI and 8X6 15 to' groun'dat contact VONI I. The release magnet operates andallows the storage' switch 430 tc restore to normal. With the switch at normal, the contact VONII is returned to normal to open the circuit to the release magnet RLS and to they upper winding of the relay SR4', and to connect ground thru armature SWIU'to the lead L5I3.` The circuit to' the lower winding of the relay* SRA Iwas opened at armature FT1 when therelay FT released'. The relay SRII' releases and-prpares circuits to the relay SW and the relay CIS. If the OSI' relay' is operated at the time the storage switchlIIllll releases, or if the OSI relay is operated after the storage switch 400 is'- released, ground on the lead L5I3 thru armatures FDI5 and OSI 2 energizs theV relay OSA which at armatures OSA3 extendsground to the armature OSI3 to operate the OS2v relay. The OS2 relay opens thej holding circuit to the OSI relay'at armature OS'22. The OSIv relay restores and vopens the circuit tothe' OSA-relay at armature 0SI2.

It'may be noted` that the operator positions such as operator position 9H) can extend calls from' the central oice 1D0 to the toll switchboard 20| over toll lines such as the toll linev 25|, by way of the call switches, suchv as the call switch 940, andthe toll line circuits, such as the toll line circ-uit 250. Assume that the `nder switch BUD has connected to an incoming'call which is tof'be'extended to the toll switchboard 20L The operator at operator-position SII) operates the necessary control apparatus to cause the call switch 940 to step its wipers tothe bank contacts aSSOCiaicdWWth-the 13011 line circuit 250, and, if

the toll line 259 is not-busy, battery thru the Winding of relay R360, armatures 353 and 324, over conductor C313 causes the call switch 940 to' switch thru to the' toll line circuit 250. Ground from the call switch 940 over the conductor C313 1 operates the relay R360 which at armature 365 opens the incomplete circuit to the relay AID over lead AI02'. Absence of battery on the conductor C251 makes the toll line circuit 25B inaccessible to 'other iinderswitches, such as the finder switch 900, and ground on the conductor C313 makes the toll line circuit 25u busy to other call switches, such as the call switch 940-.- Y

The switchboard 20I is signalled and the connection is completed as explained in detail in the specification of the Imre Molnar Patent 2,361,313, issuedOct. 24, 1944. Y

VIf''the toll-line circuitf25 is busy when called by'the operator position `SIII by means of the callswitchllll, ground on `the conductor C313 n causesthe call switch 940 to' step its' wipers-to the Vnext toll line in the group. If an idle toll line circuit isavailable, the call" switch `SII!! will switch-thrue from' battery on the-V control conduct'or, similar tothe conductor`C3-'I3,` and the connection can bev completed If anidle toll line circuit notavailable, the call switch 940 will return'la busy signal to the operator at operator position SII). The Imre Molnar Patent 2,361,313,

maybe reerred'to'for a detailedv description of the foregoing operations.V

An alarm typef-use FE is proyidedifor the storage switch 400 and`a`similar-:fus'e'is provided-for each of the other storage switches. When the fuse FE blows, battery is disconectedffrom-me relays and vmagnets of storage" switch 400 andis connected thru terminal FEI to 'thev winding4 oi thai-clay FS. .Therela-y FS,'at-armatu'reV FSI, opens afy multiple circ'zuit to Yth-*r'clayFIB-I so'tliat storage` switches'become busy, at arma-ture'FS2 connectsV ground to 'the' lead L51 2` to provide for the operation of the relay FDAand' the release of the relay FDl', at' armature' F53` connects ground to the lead 1.513 toprovidefor theoper'- ation of the' relay OSA and the'release' of the relay OSI should` thelatt'e'r be operated, and-at armature PS4 energizes the relay FA'which" is connected to Vdirectv battery at'the' fuse 'FE1 The relay FA operates" and'. at armature'r FAI connects battery to the lamp FA2'. The lampv FA2; connected to' ground over the'lead FAB, lights,I to indicate the power failure' on the'storageY switch 400.

The'storage' release key SRK whenoperated releases any operated storageY switch; such as storage switch 400 andr permits nde'r'switches, such' as the'finder switch 900,' to connect' tothe line' circuits, suchl as'the line circuit 250;'-without thel co-operation` of the storage' switches:v The operation' of the key SRK energizes the"rela`y SR1 froin'groundA at'spring SRKI.` The relay SRI Voperates and at armature SR'IIl opens the circuit to the relay' SR2: which restoresV and at armature SR24 connects ground to the lead LSII'I'. Assume that the'stora'ge'switch 400 isv connected to a marking controlv circuit, such as marking control circuit A, andthat thereiay'sSW' and SX are operated. A' circuit may be traced from ground on'the lead L5I1Iv thru' armature SW3, spring CAMI'I and the lower'winding' of the` rei lay SR'4 to battery. The relay SR'II 'operates a'n'd opens' the 'circuit to there'lay SW at armature SR42. The relay SW restores'and opensthe'circuit to the'upper winding of the' relay SX'at armatures SW6 and' SW1. The( r'elay"'SX're' stores and olosesthe'circuit to the lreleasemagnet RLSA at armature SXG." The release magnet'RLS operates and thestorageY switch llestore's" to normal as previously 'describedi' The'lead'LSUI is' multipled to all of thestorage" swltche's'in the group. Other operatedist'orag'e'switches will be'released 'in the 'same manner as' the"`s'torag"e switch 40o. y

The"relay SR2 opens the circuit' toth'erelay NS at armature SR22, disconnects the relay-'CIS from the'lead L6G2"`at armature SR23' and dis'- connects the DST lead from the'armature 'CISI at armature SR2I'to 'prevent the operation'of the'relays OAI and PAI. The'relay'NS'releases, disconnecting the relay STI' from thestorage start resistors at armature NS2' to 1. 1"e'\'1e'nt"furL ther operation' ofV the storage control'v circuit 600', and' opening a 'circuit to the relay PAZ' at armatureNSI. The relay CIS, if operated, restores whenY its circuit is openeol at armature SH23, opens a" circuit tov the relay PAZ at armature CISZ, and prepares' a circuit tothe' lead LSII'at armature CIS3L The relayPA2 restore'a'connecting ground to the lead LlII4 at armature PA'2I'.

The lead LGII is common to all of the marking control circuits, such as niarki'ngcont'rol circuit A, associated with the storage control circuit 600'. Should'al call be received now"on' the toll line circuit 250, the relay VAH) will be operatedfrom ground at armature 356 as previously described. The relay AISI at armature A13 vcloses a circuit to the lower winding of the relay`A20`f'ron1 ground Y on the lead LGI I. The relay A23 operates, corinecting battery thru the winding of` the relay R360, armature 355 and A2I over conductor C251 to thefbanks of nder'switcli'es,suchas the iind'er Sil/'ii'.clr 900, and vcoinnectiiig groiirid tolthe common-'start circuit 330oye'r- 'conductor VC253`Ii`-tlir1fx armatures A22 and AII, thus making the toll line 250 accessible to the finder switches, such as nder switch 900. The other marking control circuits associated with the storage control circuit 400 will operate in the same manner to make the toll lines .to which they are connected accessible to the finder switches.

When the key SRK is restored, the circuit to the relay SRI is opened at spring SRKI. The relay SRI restores, prepares a circuit for the OAI and PAI relays at armature SR2I, closes a circuit for the relay NS at armature SR22, prepares a circuit for the relay CIS at armature SR23, and disconnects ground from the lead L60I at armature SR24. The relay NS operates and closes a circuit to the relay PA2 at armature at NSI. The relay PA2 operates, connects the relay STI thru armatures PA23 and NS2 to the storage start resistors, and at armature PA22 connects the relay CIS over lead L602 to the storage switches. The storage switches are now operative in response to incoming calls on the toll line circuits as previously described.

The no storage key NSK is provided to prevent the storage of additional calls while permitting all stored calls to be answered under control of the storage apparatus. It may be noted that all stored calls will be answered before any subsequent calls become accessible to the operator positions and that all calls received during the interval between the operation of the key NSK and the answering of the last stored call become accessible to the operator positions simultaneously.

The operation of the key NSK opens the ciri cuit to the relay NS at spring NSKI. The relay NS restores, disconnects the relay STI from the storage start resistors at armature NS2 to prevent further operation of the storage control circuit 600 and of the storage switches in response to incoming calls on the toll lines, and opens a circuit to the relay PA2 at armature NSI. If any of the storage switches are operated, the relay CIS is energized from ground on the lead L602 and the relay PA2 is energized thru armature CISZ. The relay OAI is connected thru armatures CISI and SR2I to the lead DST. The storage control circuit 600 and the storage ldistributor 500 function as previously explained to release one of the stored calls each time an operator position answers a call. When the last storage switch releases, ground is disconnected from the lead L602 releasing the relay CIS. The relay CiS restores, opening the circuit to the relay PA2 at armature ClSZ. The relay PA2 restores and connects ground thru armatures PA2I and CiSS to the leadL6I I.

li incoming calls have been received on any of the toll line circuits, the relays corresponding to the relay A I in the marking control circuits connected to the operated toll line circuits will be operated from ground at armatures such as armature 356. rThe relays corresponding to the relay A in the marking control circuits will be operated after the release of the relay PA2 from ground on the lead L6II thru armatures corresponding to armature AIS. The seizure relays oi the operated toll line circuits are connected to the banks of nder switches, such as nder switch Sdi?, thru armatures, such as armatureAZI, and C conductors, such as conductor C257. Ground is connected to the common start circuit 930 thru armatures such as AII and A22 over conductors such as C2536. The toll line circuits on which incoming calls have been received thus become accessible to the operator positions. Subsequent incoming calls on the toll line circuit will become accessible to the operator positions in the same manner.

When the key NSK is restored, the relay NS is operated from ground at spring NSKI. The relay NS operates the relay PA2 from ground at key SCK through armature NSI. The relay PA2 connects the relay STI to the storage start resistors at armature PA23, and connects the relay CIS to the storage switches over the lead L602 at armature PA22. Subsequent incoming calls on the toll line circuits will become accessible to the operator positions under control of the storage apparatus as previously described.

The storage control key SCK is provided to make incoming calls on the toll'line circuits directly accessible tothe operator positions if no calls are in storage and operator positions are available to answer the calls, and to make the storage apparatus eiective if calls are received when operator positions are not available to answer them.

The operation of the key SCK disconnects a ground from the winding of the relay PA2. If any calls are in storage, the relay CIS is operated from ground on the lead L602. The relay PAI is open at armature CISI and is at normal. The relay PA2 is held from ground at armature PAII. Incoming calls on the toll line circuits will be made accessible to the operator positions under control of the storage apparatus as previously described. However, if all stored calls be answered, ground is disconnected from the lead L602 and the. relay CIS restores, connecting the relay PAI to the lead DST at armature CISI. If an operator position is available to answer a call, the lead DST is connected to ground at position distributor circuit 920 and the relay PAI is operated, opening the circuit to the relay PA2 at armature PAI I. The relay PA2 restores, disconnecting the relay STI from the storage start resistors at armature PA23, and connecting ground to the lead L6II at armature PA2I.

- If an incoming call is received now on the toll line circuit 250, the relay AID is operated from ground at armature 356. Ground on lead L6II thru armature A13 operates the relay A20. Battery thru the winding of the relay R360 is connected to the nder switch banks thru armature A2I over conductor C251, and ground is connected to the common start circ-uit 9130 over conductor C2536 thru armatures All and A22.

A iinder switch such as nder switch 900, under control of an operator position, such as operator position 9I0, may now connect to the toll line circuit 250, the relay R360 being operated from ground over conductor C251. The relay R360 releases the relay R350 at armature 36I, and opens the circuit to the relay AIO at armature 365. The relay AIO restores, discon- A necting ground from the lower winding of relay tures AZI, 364, 353 and A20 at armature AI3, and from the common start circuit 930 at armature AI I. The relay A20 is held by its upper winding from ground on conductor C251 thru arma- Incoming calls on other toll lines become accessible to the operator positions in the same manner as long as the relay PA2 remains normal. When there is no operator position available to answer a call, ground is disconnected from lead DST, opening the circuit to the relay PAI. The relay PAI restores and operates the relay PA2 from ground at armature PAI I. The

disconnecting ground relay`PA2 operates, connectingthe relay STI to 'the rstorage start resistors at armature PA23,

disconnecting ground from the lead LGII and connecting ground'to the lead L'I2 at armature PAN, and connecting the relay CiS to the stor- 'ages'witches over lead 1.602 at armature PA22.

ncoming calls received on the toll line circuits .willnow become accessible to the operator positions under control of the storage apparatus as previously described.

:It may be noted that 'after the storage apparatus begins'tofunction, the storage distributor 539 preeselectsa'n individual storage switch for connection to anincoming call and also makes an individual`storage switch accessible to the operator positions. A control circuit is provided for operation witha timer, which is not shown,

for operating'the storage distributor 509 to select :another storage switch if the pre-selected storage :switch :fails to Yconnect to an incoming call and-doesnot otherwise advance the storage distributor within a pre-determined time. The control circu'itland Vtimer will also operate the distributor to make another storage switch accessible to theoperator positions in case the storage switch accessible to operator positions is not released .within .a pre-determined time after 'the DST leadis grounded.

:Assumingnow that'the relay FDi is operated and that tan Ainccmingcall is received on toll line circuitlaherelay AI!) is operated from ground 'at armature $23551 as previously explained. The

minedtime thereafter, the timer again operates Li and connects ground momentarily to the pulse 2 lead. The timesrequired for the timer to connect ground to thepulse I lead should be greater than the longest hunting time required for normal 'operation of a storage switch, so that during the c normal operation of the storage apparatus neither the pulse I nor'pulse 2 leads will be grounded.

If the `storagejswitch,413,0 operates properly, the

relayAIIl 'ismreleasedyopening the circuit to the relay STI, and the relay FDA is operated from z ground on lead L5I2, releasing the relay ST2 which in turn releasesthe relay ST3. If the relay ST2 fails tovrelease, .the `relay ST3 is held operated and ground isV connected to the timer ST lead at armature SR35. After a pre-determined time, ground onthepulse ll lead energizes the upper winding ofthe relay PIthru armatures ST2? and P2I. The relay PI operates. closes its holdingcircuit from 'battery thru its lower winding, armature PII, contact P22, armatures ST33 and STZI, to ground, and connects the lower winding of the relay P2 tothe pulse 2 lead at armature PI2. After another time interval, ground is connected to the pulse' 2.. lead energizing the lower winding of the relay P2. The relay P2 operates,

opening the holding circuit to the PI relay at contact P22, opening the starting circuit to the PI relay at armature PZI, energizing itsupper winding thruarmatures P23, ST3 3 and ST2'I,1to ground, and energizing the upper winding of the relay thru armatures.Phl-FBI3, l.and

STZI, to ground.. xThe"relay'PI Vrestores fand opens thestarting circuit'ltothe-relay P2 at Aarmature PI2. The relay FAL operates, closes'V a holding circuit to its lower :winding -thru"armature PAL2 to ground at the alarm release keyflARK, and energizes the relay`ALM andthe lamp v.EDlft ALM from ground at armature'FALS. The lamp FDR ALM lights to 'indicate the abnormal'condition and the relay ALM operates, and'maygextend the alarm thru armatures ALMI and ALMZov-'er the leadsAP and FDR ALM respectively toyother points. The relay FAL energizes the upperwindingo the relay KO thru armaturesFALI, P24, FBiSfSTBB and STZI, toground, and energizes the lower winding ofthe' relay KO thru armatures KO2, ST36,;FDA3, FBI2..and-FDI I rand the winding'of the relay'FDLtobattery. The windings of the relay KO' are 4connected differentially and it does notY operate at thistime. A The relay 7PD2 operates, flrstclosing the contactsassociated with the armature FD22, thus connecting 'ground thru the winding 'of fthe relay FI, iarmatures F1333, 'PD22, FDH, PBIZ, FDAS, SISfand `KO2 to the lower winding .ofthe relay K0, Thefmagnetic eld of the lower windingoi" the relay KO is now weakened and the relay operates, opening the circuit to its lower winding at armature. KS2, opening the circuit to'relaySTZ 'atarmatureKQ I, and closing a holdingcircuit tothe relayl'Di 'at armature KOB. The relay FB2 operates'in4 full, opening the circuit to the relay FDI 'atgarmature FD23, and preparing the starting circuit vto the, storage switch l at armature FD24.

The relay ST2 restores ,when-its circuit-is opened at armature` KQL, opens` its incomplete holding circuit at armature ST2g2, openscircuits jto the relays ST3, P2 Vand KO .at Varmature ST2I, and opens the incomplete startingcircuit t o the relay PI at armature ST2?. The relayuSTBrestores and disconnects vground from th'e ti1'ner ST lead at armatureSTB. The relay P2 restores, opens its incompletdholding circuit 'at armature P23, and prepares' the starting circuit to the relay PI atarmature P-2I.l The relay KO restores, prepares the circuit toits lower-winding at armatureKOZ, and prepares the ,starting circuit for the relay ST2- at'armature KQI.

The relay STI isheld operated, from Vground thru the storage start resistor 4 and;` the timer continues to operate, alternately jconnecting ground pulses to the pulse -Ileadandjthe-pulse 2 lead at regular intervals. After `the relays KO, ST2 and ST3 have released,;the relay ST2 isoperated from ground thru armaturesKOI and FDAl, contact ST3I, and armatures "STI3 A and VTSS. The relay ST2 closes a circuit 'to' the relay ST3 at larmature ST2 I, connects .ground thru armatures ST23, FDAand F1324 to the lead L52I to start the storage switch MIL'and connects the relay PI 'to the'pulse I lead atarmature ST2?. If thev storage switch '42| connects'to the marking control' circuit Afthe relay -AIUwill be released, as previously described, and the" circuit to the relaySTI willfbe opened at armature AIE. The relay YSTI restores 'andfdiscgnnects a ground from 'the timer'ST leadatarmatureiSTI I. The FDA relay will )ce operated when'the storage switch 4M connects to the markingcontrol circuit A from ground Yon. the vlead, 11522 .and `will open the circuit to relay ST2. RelaySTZ releases and opens the-circuitto relay ST3. The storage distributor 5ml loperates as previously described.

The relay ST3 restores and disconnects ground 2l from the timer ST lead at armature ST35, thus stopping the operation of the timer.

If the storage switch 40| does not connect to the marking control circuit A within the allowed time, the relays PI and P2 operate as described in the foregoing and the storage distributor 500 will select another storage switch for operation.

Assume now that the storage switch 400 is connected to the marking control circuit A and is accessible to the operator positions. The relays SW and SX in storage switch 400 are operated, the relay OSI in storage distributor 500 is operated, and the relay FDI in storage distributor Sill) is normal. When an operator position is ready to answer a call, the relay OAI is operated from ground on the DST lead as previously described. The relay OAI closes a previously traced circuit from ground at armature OAII thru the winding of the relay OA2 and the lower winding of the relay AS in series. The relay OA2 connects ground to the timer ST lead at armature OA2I to start the operation of the timer, and connects the upper winding o f relay TI to the pulse I lead at armature OA2'2; The relay AS operates and connects the lower winding of the relay 'SX thru armatures ASZ and SX3 over the lead L603 to the armature T24. Ifthe storage switch 400 is not released within a pre-determined time, a momentary ground on the PI lead thru armatures OA22 and T23 energizes the upper winding of the relay TI. The relay TI closes a holding circuit from battery thru its lower winding thru armature TII, contact T22 and armature OA23, to ground, and, at armature TI2, connects the lower winding of the relay T2 to the pulse 2 lead. If, after another time interval, the storage switch 400 has not been released, a momentary ground on the pulse 2 lead energizes the lower winding of the relay T2. The relay T2 operates, closes a holding circuit from battery thru its upper winding thru armatures T2I and OA23, to ground, opens the holding circuit to the relay TI at contact T22, opens the starting circuit to the relay TI at armature T23, and energizes the lower winding of the relay SX from ground thru armature T24. The relay TI restores and disconnects the lower winding of the relay T2 from the pulse 2 lead at armature TI2,

The windings of the SX relay are connected differentially and it releases when its lower winding is energized. The relay SX opens the circuit to its upper widing at armatures SXI and SX2, opens the circuit to its lower winding at armature SX3, and, at armature SX6, opens the circuit to the relay SW and closes the circuit to the release magnet RLS. The relay SW restores and the release magnet RLS operates allowing the storage switch 400 to restore to normal. Ground thru spring VONII and armature SWIU is connected to the lead L5I3 and thru armatures FDI5 and OSI2 to the winding of the relay OSA. The series circuit to the relays OA2 and AS is opened at armature SWS when the relay SW restores. The relay OA2 restores, disconnects ground from the timer ST lead at armature OA'2 I, opens the incomplete starting circuit to the relay TI at armature OA22, and opens the holding circuit to the relay T2 at armature OA23. The relay T2 restores, prepares the starting circuit to the relay TI at armature T23, and disconnects ground from the lead L603 at armature T24. The relay OSA operates, connecting ground thru armatures OSA3 and OSI3 to the winding of the relay OS2. The relay OS2 operates, opening the holding circuit to the relay OSI which restores and opens the circuit to the relay OSA at armature OSI2. A circuit is also prepared thru armatures OSI3 and OS23 to the next OS relay in the distributor. The relay OSA restores, and if the storage switch 40! is connected to a marking control circuit, the call stored therein becomes accessible to the operator positions as previously described.

At the time the relay AS operates in series with the relay OA2, ground thru armatures AS3, SX4 and SW4, wiper WI3 contact B13, armature AI2 and the upper winding of the relay A20, to battery operates the relay A20, which closes its holding circuit at armature A24, and opens the circuit'to the lower winding of the relay AID at armature A23. The relay All! operates and ground is connected to the common start circuit 938 thru armatures AII and A22 over conductor C2536. The toll line circuit 250 becomes accessible to the operator positions without the co-operation of the storage apparatus.

As previouslydescribed, the relay FAL, operated after the P2 relay operates, closes a holding circuit to itself thru armature FAL2 and the alarm release key ARK. The relay FAL lights the lamp FDR ALM indicating that one of the storage switches has failed to connect itself to an incoming call within the normal time. The relay FAL remains operated until the key ARK is operated. The operation of the key ARK releases the relay FAL, if the relay P2 is not operated, and the relay FAL in releasing extinguishes the lamp FDR ALM.

The routine test key RTK provides a means for testing the storage apparatus. This test should be started when all the storage switches are at normal. It isV therefore necessary to operate the key NSK to release the relay NS and to allow the relay PAZ to release when the last operated storage switch releases. As each storage switch releases, the corresponding OS relay in the storage distributor 500 is released and the succeeding OS relay is operated. Finally, the OS relay associated with the storage switch, pre-selected by the storage distributor 500 to hunt for an incoming call, is operated. The FD relay associated with the storage switch is operated and further operation of the OS relays is prevented.

Assume that the relays FDI and OSI are operated and the storage switch 400 is in normal position. Ground is connected to the lead L5I3 thru spring VONII and armature SWIG. The circuit to the relay OSA is opened at armature FDI5 and the relay OSA cannot operate to close the starting circuit to the relay OS2 thru armature OSA3.

The operation of the key RTK closes a circuit from ground thru armatures OSA4, PA24 and NS4, spring RTKI, armatureTSZZ and the lower winding of the relay TSI to battery. The relay TSI operates, closes a circuit from ground at armature TSII over the lead LGI'I to vertical bank contact 3, and thru storage start resistor 9 thru armatures TSI2 and FBZI, to the relay STI; connects battery thru armature TSI3 over the lead L6I6 to the contact B24, and opens the incomplete starting circuit to the relay TS2 at armature TSI4. The relay STI operates and the storage control circuit 600 functions as previously described to start the hunting operation of the storage switch 403. The relay FT, at the time, is operated from ground thru armatures ST23, FDA4 and FDI3 over the lead LSI I.

The storage switch 400 steps its wipers to the ninth level where groundon verticalbank con- 

